Increasingly strict statutory regulations regarding admissible pollutant emissions from motor vehicles, in which internal combustion engines are disposed, make it necessary to keep the pollutant emissions as low as possible during operation of the internal combustion engine. This may be done firstly by reducing the pollutant emissions that arise during combustion of the air-fuel mixture in the respective cylinder of the internal combustion engine. Secondly, in internal combustion engines exhaust gas after-treatment systems are used, by means of which the pollutant emissions produced during the process of combustion of the air-fuel mixture in the respective cylinders are converted into harmless substances. For this purpose for example catalytic exhaust converters are used, which convert carbon monoxide, hydrocarbons and nitrous oxides into harmless substances. In this connection for example so-called three-way catalytic converters are used.